BHE Field Design by Superposition of Effects in Space and Time

Dimensionless temperature on the BHE surface, for a single BHE and for the most critical BHE in a line of 3 with a dimensionless distance equal to 40 (Fo = 4400).

A design method for BHE fields in the absence of groundwater flow is presented, based on the superposition of effects. The effects of any periodic heat load with a period of one year can be obtained by a weighted sum of the effects of a monthly unit step heat load, properly displaced in time. The interference among BHEs is evaluated by the superposition of effects in space. The result of the computations is a set of dimensionless equations that, properly superimposed, yield the time evolution of the dimensionless temperature at the interface between the most critical BHE and the ground, for a period of 50 years, for several typical configurations of BHE fields.